Transcript Thyroid diseases by Dr Sarma hand out

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Thyroid Function Tests
1. TSH (normal range 0.3- 4.0 mU/L)
2. Free T4 (normal range 0.7- 2.1 ng/dL)
3. Free T3 (normal range 1.4 - 4.4 pg/dL)
4. Anti-Thyroid Antibodies (TPO Ab, TSI)
5. Nuclear Scintigraphy ( I123 or TC 99m)
6. FNAC of nodule
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What tests should I order ?
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As per the Guidelines of the AACE and ATA, ITS
1. TSH alone if Hypothyroidism is suspected
2. TSH and Free T4 only if Hyperthyroidism is
suspected or for routine evaluation
3. Free T3 if T3 toxicosis is suspected
4. For follow-up of treatment only TSH
5. Don’t order for Total T4 or Total T3
6. Never order RIU in pregnancy or lactation
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FREE THYROXINE or FT4
NINE SQUARES MAJIC
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PRIMARY
HYPERTHYROID
NTI or Patient is
on ELTROXIN
SECONDARY
HYPERTHYROID
SUB-CLINICAL
HYPERTHYROID
EUTHYROID
SUB-CLINICAL
HYPOTHYROID
SECONDARY
HYPOTHYROID
NON THYROID
ILLNESS - NTI
PRIMARY
HYPOTHYROID
NORMAL
HIGH
LOW
THYROID STIMULATING HORMONE - TSH
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The Commandments

Suspect hypothyroidism ever

All obese patients TSH a must

Growth and pubertal delay

For all pregnant -test TSH, FT4

Unexplained depression

Postmenopausal 15% Hypothy

TSH is the test in Hypothy.

Start low and go slow

TSH, FT4 to confirm Dx.

Use L-Thyroxine only

Nine square magic

Always on empty stomach

Test cord blood for TSH

Thyroxine - avoid empirical use
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Algorithm for Hypothyroidism
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Measure TSH
Elevated TSH
Normal TSH
Measure FT4
Considering Pituitary
Normal
Low
Sub-clinical hypo
TPO +
T4 repl
TPO Annual FU
No
Primary hypothyroid
TPO -
TPO +
Hashimoto
Others
Yes
No tests
Low
Evaluate Pituitary
Sick Euthyroid
Drugs effect
Measure FT4
Normal
No tests
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Algorithm for Hyperthyroidism
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Measure TSH and FT4
 TSH, FT4 N
 TSH,  FT4
Primary (T4)
Thyrotoxicosis
 TSH,  FT4
Pituitary Adenoma
Measure FT3
Features of Grave’s
Yes
Rx. Grave’s
No
 RAIU
Low RAIU
Single Adenoma, MNG
N TSH, FT4 N
FNAC, N Scan
High
T3 Toxicosis
Normal
Sub-clinical Hyper
F/u in 6-12 wks
Sub Acute Thyroiditis, I2, ↑ Thyroxine6
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Causes of Hyperthyroidism
1.
Graves Disease – Diffuse Toxic Goiter
2.
Plummer’s Disease – Toxic MNG
3.
Toxic phase of Sub Acute Thyroiditis - SAT
4.
Toxic Single Adenoma – STA
5.
Pituitary Tumours – excess TSH
6.
Molar pregnancy & Choriocarcinoma (↑↑ βHCG)
7.
Metastatic thyroid cancers (functioning)
8.
Struma Ovarii (Dermoid and Ovarian tumours)
9.
Thyrotoxicosis Factitia ; INF, Amiodarone, SSRIs
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Summary of Hyperthyroidism
Hyperthyroidism
Age
%
Enlarged
Pain
RAIU
Treatment
None
↑↑
ATD – 18 m
↑
RAI, Surgery
±
RAI, ATD
↓↓
NSAID,
Steroids.
Graves (TSI Ab
eye, dermo, bruit)
20 - 40
60%
Diffuse
Toxic MNG
> 50
20%
Lumpy
Single Adenoma
35 - 50
5%
Single
None
Any age
15%
None
Yes
S Acute Thyroiditis
Pressure
TSH is markedly low, FT4 is elevated
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Anti Thyroid Drugs (ATD)
Imp. considerations
Methimazole
Propylthiouracil
Efficacy
Very potent
Potent
Duration of action
Long acting BID/OD
Short acting QID/TID
In pregnancy
Contraindicated
Safely can be given
Mechanism of action
Iodination, Coupling
Iodination, Coupling
Conversion of T4 to T3
No action
Inhibits conversion
Adverse reactions
Rashes, Neutropenia
Rashes, ↑ Neutropenia
Dosage
20 to 40 mg/ OD PO
100 to 150mg qid PO
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Algorithm for Thyroid Nodule
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Thyroid Nodule
Low TSH
Normal TSH
TC 99 Nuclear Scan
Hot Nodule
RAI Ablation,
Surgery or
ATD
FNAC or US guided
biopsy
Cold Nodule
4%
Malignant
Surgery
10%
69%
Suspicious or
follicular Ca
Benign
T4
suppression
Cyst
17%
Non diagnostic –
repeat FNAC
Surgery or
Cytology
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